Riparian Management
We simply have to look after our waterways and improve their ability to sustain not just eels but all our native species.
A clean waterway by itself is not enough to enable a healthy eel population. A concrete lined watercourse or drain might hold a few eels but what they really need is shelter – root masses, mud, holes and places to hide out during the day waiting for nightfall and opportunities to forage. Small eels are particularly vulnerable if they can’t hide away from predators including larger eels.
Niwa have completed comprehensive work on riparian margins and management. Click Here to link to their work.
Riparian trees and plantings carry heavy loads of insects providing food along with the shade which will keep the water cool during the summer.
Waterways with willow, kahikatea or other trees planted along their margins carry much greater and healthier populations of eels.
Whilst we readily welcome riparian restoration initiatives which, if well designed can dramatically improve eel habitat, we are really concerned that some local bodies are indiscriminately pulling out or poisoning willows to replace them with grasses and flaxes.
We recommend instead, a more transitioned approach where natives are replanted behind the existing established riverbank trees. In 20-50 years their root systems will extend to the water and they will be effective for bank consolidation and useful as eel habitat. Once large enough, New Zealand natives tend to overwhelm willows, in many cases negating the need for culling.
Whilst we have extolled the virtues of willows for pastoral riparian margins, we are also greatly in favour of those native trees which can handle wet feet and have extensive root systems. It should be remembered however, that natives take a long time to grow.
We simply ask that better species of willows are not removed until replacement natives have grown to a significant size.
Superior riparian plantings consolidate river banks, stopping erosion and reducing silt loading to our coastal estuaries and waters.
Keeping grazing stock away from watercourses and lake foreshores is a fundamental to riparian management. Stock damage stream, lake and river banks and margins.
With direct access, their faeces and urine directly pollute and nitrify the water without the opportunity to be biologically filtered and processed through soil and grasses.
THE LEVEL OF SILT REACHING COASTAL WATERS IS OF GREAT CONCERN!
It is certainly damaging our valuable rock lobster and paua fisheries and causing downstream lakes to become excessively shallow and often eutrophic.
Terra Moana & Moana NZ have completed detailed work on the damage caused by silt flowing into our coastal waters. To learn more Click here.
Eels do not thrive in close proximity to pine forests.
We recommend widening the margins between streams and exotic forestry.
Good river conditions don't just benefit Tuna, the ecosystem as a whole is improved. To read more on how this helps the whitebait population Click Here.
Landcare Research have published work specifically looking at the importance of willows vs natives for pastoral riparian margins and flood control. Click Here to read more about this work.